/*
 * Copyright Camunda Services GmbH and/or licensed to Camunda Services GmbH
 * under one or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information regarding copyright
 * ownership. Camunda licenses this file to you under the Apache License,
 * Version 2.0; you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.camunda.bpm.engine.impl.tree;

import java.util.Collection;
import java.util.Collections;

/**
 * @author Thorben Lindhauer
 */
public abstract class SingleReferenceWalker<T> extends ReferenceWalker<T> {

  public SingleReferenceWalker(T initialElement) {
    super(initialElement);
  }

  @Override
  protected Collection<T> nextElements() {
    T nextElement = nextElement();

    if (nextElement != null) {
      return Collections.singleton(nextElement);
    }
    else {
      return Collections.emptyList();
    }
  }

  protected abstract T nextElement();
}
